Elastomeric structures having controlled surface release characteristics

ABSTRACT

Elastomer structures having exposed controlled surface release characteristics can be made by coating at least a portion of their surface with a releasing composition comprising (a) a chlorosulphonated polymer; (b) a reinforcing filler and (c) a green tackifying agent. Optionally, these compositions can also contain a chemical curing system and one or more volatile solvent/diluent viscosity-reducing vehicle. In a specific example, the coating are applied to flexible structures used in machines for the manufacture of articles having natural tack due to their rubber or elastomer content.

FIELD OF THE INVENTION

This invention relates to elastomeric structures having controlledsurface release characteristics. More specifically, it relates toflexible structures and machinery components wherein the releasecharacteristics are controlled with a surface coating which releases orinhibits adhesion of naturally sticky or tacky materials with which thecoated surface may come in contact. In a particular embodiment, thisinvention relates to flexible diaphragms, bladders, bags, rolls, sleevesand the like with or without fabric reinforcement having controlledsurface release coatings which are useful in tire assembly machines(TAMs). These coated flexible structures readily release partiallyassembled tires and thus facilitate their efficient manufacture. Theinvention also relates to exposed release surface coatings, methods andintermediates for making same, and tire building methods employing them.

BACKGROUND OF THE INVENTION

The problem of releasing manufactured articles and processed goods fromflexible machinery components with which they may come is contact is arecurring one that arises in many varied situations. Unless it isadequately solved, undesirable adhesion of the materials or goods anyhinder or even block assembly and conveyor lines. In extreme cases, thearticles and goods as well as machinery can be damaged by such blockage.The problem is particularly prevalent with elastomeric structures orcomponents such as conveyor belts and devices such as flexiblediaphragms, bags, bladders, sleeves and the like which are often made ofelastomeric materials such as rubber which possess natural stickiness ortack. The solution of such problems in convenient, safe and efficientmanner allows high speed manufacturing and processing operations withminimal damage and delay. The solution of such problems may be complexbecause some degree of adhesion is usually desirable or necessary toallow efficient functioning. If machinery components are too slick,improper positioning of components and work pieces can occur. Thereforeit is optimum to have a means of controlling surface adhesioncharacteristics as the present invention provides.

The present invention is directed to convenient, safe, economical andexpeditious means for controlling the natural surface tack or stickinessof flexible elastomeric structures and machinery components such asbelts and polymeric diaphragms such as found in bags, bladders, sleeves,and the like. It comprises forming on the flexible surface whichcontacts the articles or goods, an exposed controlled adhesive releasecoating which is fracture (that is, crack) resistant. Surprisingly thissurface coating or film can be formed from materials which is some caseshave previously found use as components of adhesives or bonding agents,an application that is antithetical to the purpose they serve in thepresent invention. In one embodiment of the invention, the surfacerelease coating is applied or formed on at least a portion of thesurface (usually the outer surface) of a flexible diaphragm which,through inflation or other mechanical means, exerts pressure on anaturally sticky article such as one made of rubber. In otherembodiments, the invention is employed in conveyor belts and molds whichcontact such diverse materials such as thermoplastic articles and frozenfood goods during their collection, processing and storage. Forconvenience and brevity, the use of the invention in the formerapplication will be discussed in detail below. By so doing, it is to beunderstood that the full scope of the invention is in no way therebylimited.

Machines for the assembly of tires (TAMS) contain elastomeric structuressuch as inflatable rubber bladders which are conventionally used forsuch manufacturing operations as turning up ply ends over bead rings andagainst plies on the TAM mandrel or drum. These rolling, inflatableturn-up bladders (TUBS) turn the ends of the plies wrapped on the tirebuilding mandrel up around the bead rings and over them against the plymaterial. The rubber ply material is tacky by nature, and it is thistack which causes the plies to stick together and thus maintain theintegrity of the partially built or green tire. The TUBS areconventionally made from vulcanized rubber, natural, synthetic ormixtures of the two with optional fabric reinforcement, and the tackyply ends have a tendancy to stick to the outer surfaces of the bladderwhich turn them up, particularly, since the inflated bladders exertpressure on the turned-up ply ends. This adhesion tends to retard theretraction of the deflated bladders, and it can also result in erosionof the bladder material coming in contact with the ply ends. Thus it isdesirable to provide TUBS with surfaces which are non-adhesive orreleasing to the tire plies with which they may come in contact. Onesolution to this problem is found in U.S. Pat. No. 4,381,331 to Johnson,which describes a ply turnover bladder having at least a portion of itsouter surface comprising a fabric layer of spaced cords calendered witha coating of unvulcanized, uncured rubbery polymer, the spaces betweenthe cords being free of said polymer at the surface so that the cordsproject above said surface. It has been found that this structure hasreduced tendency to adhere to the rubber ply of tire components and thusrelease the tire during its manufacture. Naturally, the construction ofthe Johnson bladder is somewhat complex, involving several manufacturingand, particularly, finishing steps which must be carefully controlled toachieve the desired controlled adhesive surface. For this reason,Johnson bladders are expensive to make.

Another related embodiment of this invention is found in tire curingbladders having an outer releasing surface coating and in a method ofcuring tires utilizing such coated bladders. Conventionally, pneumaticrubber vehicle tires are produced by molding and curing a green oruncured and unshaped tire in a molding press. In the press, the greentire is pressed outwardly against the mold surface by means of an inner,fluid-expandable bladder. By this means the green tire is shaped againstthe outer mold surface which defines the tires tread pattern andconfiguration of the sidewalls. Generally, the bladder is expanded byinternal pressure provided by a fluid such as hot gas, hot water, and/orsteam. The use of such tire curing bladders is well known in the art oftire manufacture. It is also known that difficulties may occur betweenthe bladder and the inner surface of the tire if there is excessiveadhesion, that is, the lack of release between the two. Typically, thisresults in deterioration of the bladder, misshaping of the tire in themold, and similar problems. Furthermore, air bubbles can potentiallybecome trapped between the bladder and tire surfaces and promote tirevulcanization defects. For this reason, it is conventional practice toprecoat the inner surface of the green or uncured tire with a lubricantin order to provide lubricity between the outer bladder surface and theinner tire surface. Such lubricants have sometimes been called liningcements, band ply dopes and bag dopes. Conventionally, the inner surfaceof the green tire, which is typically a rubber gum stock, is simplyspray coated in a combined ventilated spray booth with a lubricant whichmight, for example, be based on silicone polymers. Other additives mayalso be conventionally utilized in this application, such as mica,polymeric materials, polyols, polyethers, clays, and the like. Anotherapproach to this problem is the alternative of coating the bladderitself. One such example of a tire curing bladder lubricant is found inU.S. Pat. No. 4,359,340, to Comper, et al, which describes an aqueouslubricating composition for tire curing bladders containingpolydimethylsiloxane, a silane, a surfactant and, optionally, a metalsalt of an organic acid.

Still another means of solving the problem of undersirable adhesionbetween tacky tire plies and similar elements and flexible TAMcomponents such as bladders and sleeves is the so-called Red Releasecoat developed by The Firestone Tire & Rubber Company. This coatconsists of a polymeric film formed from a fluxed (that is,heat-treated) blend of PVC and a copolymer of butadiene andacrylonitrile (for example, Paracril OZO). This material is available asa thin sheet that is cemented to the bladder or sleeve on which therelease coating is desired. The red release coating can be subject tocracking during use. Such cracks have been found to propagate into theflexible underlying elastomeric structure and thus cause prematurefailure of the component. One of the cements used in adhering the redrelease coat to flexible diaphragms such as bladders, sleeves, bags andthe like is Chemlok-234B, which is described in more detail below.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a fractureresistant, surface coating of controlled release characteristics forelastomeric structures such as flexible diaphragms, bladders, bag, andsleeves and the like. Such release coatings allow rapid, unimpededrelease of green tires and other rubber articles during their formation,construction and processing. Another object of the invention is toprovide a bladder having a fracture resistant releasing surface coating.Another object is to make bladders with more design freedom, and, forexample, a TUB with flexible nose which in turn produces a tighter beadturn-up. It is still another object of the invention to provide aprocess for manufacturing such elastomeric structures (e.g., bladders)and a process for manufacturing tires and other tacky articles usingsuch release coated structures. Other objects of the invention willappear in the course of the description thereof which follows.

The above-mentioned objects can be achieved by the practice of theinvention which in one embodiment comprises a fracture resistant,exposed release surface coating of release-effective thickness for anelastomeric structure formed by the method which comprises the steps of:

(I) applying to at least a portion of the surface of the structure areleasing composition comprising:

(a) a chloro-sulfonated polymer;

(b) a reinforcing filler;

(c) a green tack agent; and optionally

(d) a suitable chemical curing system; and, optionally,

(e) a first inert, volatile solvent/diluent viscosity reducing vehiclefor (a)-(d); and, optionally,

(f) a second inert, volatile solvent/diluent viscosity reducing vehicle;

(II) removing a sufficient amount of the first and second vehicle toform a coherent adhering film; and

(III) curing the film to form the exposed release coating.

Other embodiments of the invention include flexible elastomericstructure having controlled release characteristics through the presenceon at least a portion of their surface of a crack resistant releaseexposed surface coating formed as described above in accordance with theinvention and methods for making such elastomeric structures such asbladders, bags, diaphragms, rolls, sleeves and the like with theaforedescribed releasing surface coating as well as for forming thecoating. Machines, for example, TAMs comprising such elastomericstructures (e.g., bladders) and methods of making and using them arealso within the scope of the invention as are methods for using them.

DETAILED DESCRIPTION OF THE INVENTION

Materials suitable for a practice of the present invention are in manycases generally known to those of skill in the art. In other cases, theycan be prepared by those of skill in the art without undueexperimentation or hardship. For example, chlorosulfonated polymers,particularly chlorosulfonated hydrocarbon polymers are known to the art.In many cases those chloro-sulfonated polymers exhibiting elastomericproperties are useful in the practice of the present invention. Aparticular class of chloro-sulfonated polymers are the chlorosulfonatedpolyethylenes known to the rubber industry. Such materials are describedin the literature; see, for example, the Vanderbilt Rubber Handbookpublished by the R. T. Vanderbilt Company of Norwalk, Conn., U.S.A.(1978) particularly pages 300-307. A series of commercially availablechlorosulfonated polyethylene is sold by the E. I. duPont de Nemours andCompany of Wilmington, Del., U.S.A., under the trade name Hypalon.Hypalons are thermoplastic elastomers which are available in at leastsix grades designated as Hypalon 20, 30, 40, 4085, 45 and 48. Thesematerials have Mooney viscosities [ML 4' at 100°C. (212°F.)]of 28 plusor minus 6, 31 plus or minus 7, 56 plus or minus 5, 98 plus or minus 8,37 plus or minus 6 and 78 plus or minus 8, respectively. Hypalons can becured with a variety of systems including metallic oxides, sulphurbearing organic compounds and epoxy resins. Organic rubber accelerators,particularly those containing nitrogen, may also be used in the curesystem; other curing systems such as peroxide curing systems andcyanurate systems can also be used. Hypalon solutions have been used incoatings because the resulting films have excellent colorability andweatherability. Practical solvents for Hypalons include toluene,trichloroethylene, 1,2-dichloroethane, and dichlorobenzene. Theabove-noted Vanderbilt Rubber Handbook is hereby incorporated byreference for its disclosures relating to Hypalon and similar materialsand their uses.

Reinforcing filler materials useful in the practice of the presentinvention are also well known to those of skill in the art. See, forexample, the above-referenced Vanderbilt Rubber Handbook, particularlypages 347-349. Typical fillers include carbon black and silica. Manygrades of carbon black suitable for use in the present invention areavailable. Particularly useful are those having surface areas (EMSA) ofat least 20m² /g. and more preferably at least 35m² /g. up to 200m² /gor higher. Surface area values recited in this application are thosedetermined by ASTM test method D-1765 using the cetyltrimethyl-ammoniumbromide (CTAB) technique. A typical example of useful carbon blacksinclude superabrasion furnace (SAF) blacks, high abrasion furnace (HAF)blacks, fast extrusion furnace (FEF) blacks, fine furnace (FF) blacks,intermediate superabrasion furnace (ISAF) blacks, semi-reinforcingfurnace (SRF) blacks, medium processing channel blacks, hard processingchannel blacks and conducting channel blacks. Various grade of suchblacks are referred to in the trade by their ASTM designations (D1765-28a) N-110, N-220, N-339, N-330, N-550 and N-660. Other reinforcingmaterials such as fumed silica, silica dioxide and various type of clayknown to those of skill in the art to exert reinforcing action onelastomer compositinos containing them can also be used. Modified carbonblacks, particularly those modified with organonitrogen compounds canalso be used as can other black reinforcing fillers such as bituminousfine black, ground and pulverized anthracites and other mineral blacks.Austin Black 325, Carb-O-Fil and Kenmix SRF Carbon Black/G are specifictypical examples of these materials.

The releasing compositions used in the practice of the present inventionalso contain a green tack agent (in this context, green refers touncured, unvulcanized rubber or elastomer, not to color). Typically,this material is a resin which functions to maintain a certain degree ofadhesion of the surface coating to the underlying surface of theelastomeric structure being coated, particularly during the initialstages of coat formation. The green tack agent may also aid duringcuring to strengthen the three dimensional network coating. Manysuitable green tack agents are known to those of skill in the art. See,for example, the compendium entitled Materials and CompoundingIngredients for Rubber, published by Rubber World magazine, a subsidiaryof Bill Communications Inc., New York, NY, U.S.A. (1975), particularlypages 198-205, which are hereby incorporated by reference for theirdisclosure relating to green tack agents (tackifiers) useful in thepresent invention. Among the specific types of useful tackifiers arealkylphenol/formaldyhyde resins, 70 percent chlorinated paraffin resins(Chlorez 700), poly(beta) terpene resins (e.g., Croturez),dehydroabietic resins, ethylene vinyl acetate, chlorinated polyethyleneresins, modified petroleum resins (Picco series from Hercules, Inc.),the polyterpene resins (e.g., Piccolyte series of resins), thechlorinated paraffin oil resins (Paroil 2400A - Chlorovis 150A fromDover Chemical Co.), the pine wood tar resins, the aromatic petroleumhydrocarbon resins and various metal resinate compositions. Particularlyuseful are the hydrocarbon green tackifying agents, the chlorinatedparaffin resins such as Chlorez 700, the terpene and poly(terpene)resins (and their chlorinated and brominated analogs) and halogenatedpolyolefin resins such as chlorinated polyethylene resins of molecularweights (Mn) about 1000 to 30,000.

In many instances the releasing compositions of this invention contain achemical curing system containing sulphur and/or nitrogen which issuitable for promoting curing (vulcanization) of the composition andparticularly the polymer(a). In some instances, particularly where thepolymer(a) is thermoplastic and/or capable of self cure, particularlyafter a period of storage or use, or the composition is subjected tocuring high energy radiation, inclusion of a chemical curing system isnot required. Therefore, in its broad aspect, the releasing compositions(and the method of forming and exposed releasing coating) of thisinvention, the use of a chemical curing agent is optional. Also optionalis the use, where appropriate, of sensitizers and similar adjuvants forcuring in those systems which are self curing or radiation curing.Typically, however, the releasing compositions of this invention containa sulfur and/or nitrogen-containing curing system.

Many suitable curing systems for the components of the releasingcompositions of the present invention are known. Among these thesulphur-based systems are common, particularly those also containingconventional amounts of nitrogen-containing accelerator and activatorcompounds. Other chemical cure systems can also be used. When thechloro-sulfonated polymer is a Hypalon (or mixture containing Hypalon)various known systems such as metallic oxides (litharge, magnesia),sulphur bearing organic compounds and epoxy resins can be used.Peroxides, particular in combination with nitrogen compounds such astriallyl-cyanurate can be used. Commercial sulphur systems such asSulfads and Methyl Tuads plus sulphur can also be employed. It is alsopossible, in certain instances, to cure the release compositions withhigh energy electromagnetic radiation.

The releasing compositions of the present invention also containoptionally one or more inert, volatile, viscosity-reducing solventdiluent vehicles. These vehicles aid primarily in providing thereleasing composition with a convenient means of application throughreducing its viscosity and functioning to solublize or to stabilydisperse the composition so that it may be conveniently applied in thinfilms. A solvent diluent in the context of this application is anorganic liquid having a boiling or evaporation range of approximately20°-200°C. at atmospheric pressure and which is capable of eitherdissolving or stabily dispersing the various components of the system asdescribed above to form a homogeneous, relatively nonviscous liquid thatmay be applied by painting, dipping, spraying, or other suitabletechniques.

The release coatings of the present invention are surface coatings; thatis, they coat at least a portion of the surface of the elastomericstructures on which they are used. The surface is often an outer or topsurface, for example of a bag, bladder, or belt, but in the case of asleeve or constricting device, it may be an inner surface. In any eventit is an exposed surface; there is no additional layer or film coveringit and the coating makes more or less direct contact with the object,article, or good it is intended to release or prevent adherence of.

Among the solvent/diluents that can be used in the practice of thepresent invention are hydrocarbon solvents such as liquid alkanes andcycloalkanes of about 6-12 carbons and liquid aromatic solvents of 6-12carbon atoms, particularly benzene, toluene and the various xylenes.Mixtures, typically commercial solvents, such as varsol, gasoline, VM&Pnaphtha, kerosene, and similar materials also are useful Halogenated,and particularly chlorinated, liquid alkanes and aromatics can also beconveniently used. Among specific examples are chlorocyclohexane, 1-1dichloroethylene, perchloroethylene, perchloroethane, chloroform,chlorobenzene, benzene, toluene, chlorotoluene, M-xylene and mixtures oftwo or more of these. These soluent diluents are generally inert to theother components of the releasing composition, that is, they do notdetrimentally interfere with the functioning of the components for theirintended purpose. They are used in amounts suitable to reduce theviscosity of the composition to desirable levels, generally to levelsapproximating the viscosity of the solvent/diluent itself. Typically,such amounts will be approximately 10-15 volume percent of the releasingcomposition up to as much as approximately 60-90 volume percent of thecomposition. In certain cases the amount of solvent/diluant can be ashigh as 90-95 volume percent of the releasing composition.

In certain embodiments of the invention, it is convenient to use thesolvents in two stages. Because of this, it is convenient to refer to afirst and second solvent/diluents. These constitute different stages ofdilutions rather than distinct materials. Thus, optionally, thereleasing compositions of the invention may contain a firstsolvent/diluent and a second solvent/diluent. This is usually done forconvenience of handling and transport of a concentrate. Thus, a basereleasing composition can be made up with a certain amount ofsolvent/diluent in a relatively concentrated form which is economical tohandle, ship and store. Then, before use, this concentrate is furtherdiluted with a second solvent/diluent to provide the final formulationhaving the desired viscosity properties which facilitate application.Generally, the first and second solvent diluents are both chosen fromthe aforedescribed classes of solvents. For example, a firstsolvent/diluent may be a mixture of perchloroethane and chlorotoluene(50/50) constituting a total of about 75 percent by volume of theconcentrated release composition and the second solvent/diluent may betoluene or xylene. This second batch of solvent/diluent may be used inamounts ranging from about 0.5-3 parts per 1 part of concentratedreleasing composition containing the first solvent/diluent constituting50-70 percent by volume of the concentrated composition. Generally, thepractice of the invention is not dependent on a particular choice offirst and/or second optional solvent/diluents nor on the use of specificproportions thereof.

                  TABLE I                                                         ______________________________________                                        Releasing Composition                                                         COMPONENT          PARTS BY WEIGHT                                            ______________________________________                                        (a) Chlorosulfonated Polymer                                                                     10-100                                                     (b) Reinforcing Filler                                                                           20-200                                                     (c) Green Tackifying Agent                                                                       10-90                                                      (d) Curing System (if present)                                                                   0.1-10                                                     (e) First Solvent/Diluent                                                                        As Needed*                                                 (f) Second Solvent/Diluent                                                                       As Needed*                                                 ______________________________________                                         *To provide desired viscosity                                            

The various components of the release surface coatings of this inventionare used in generally effective amounts. Table I shows the preferredrange of parts by weight of each of essential component (a)-(c). Otherdesirable but non-essential components are used in suitable amounts asare the solvent/diluents.

The aforedescribed components of the releasing compositions of thepresent invention can be combined by suitable techniques well known tothose of skill in the art such as mixing, blending, compounding and thelike. When the materials are available as solids, it may be necessary tofirst grind or dry mix them or, typically, dissolve them in a compatibleinert solvent as described above to facilitate their dispersion. The useof mechanical mixers and agitators may be convenient and such devicesare well known. In a typical embodiment, the various components of therelease composition are blended with a convenient amount of inertsolvent/diluent to form a homogeneous blend which is stored until used.Then the additional amounts of solvent/diluent are added to produce thefinal composition of desired viscosity.

The release composition can contain various adjuvants and supplementalingredients such as pigments, fillers, accelerators, retardants,anti-degrandants, and the like which enhance and improve theeffectiveness of these inventive release compositions. While desirable,such added materials are not essential to satisfactory practice of theinvention.

Application of the release coating compositions, and formation of therelease coating can be accomplished by suitable techniques known tothose of skill in the art such as painting, spreading, dipping, sprayingand the like. Generally, satisfactory practice of the invention is notdependent on a particular means of applying the releasing composition tothe elastomeric structure to be coated. The release surface coating isformed in a release effective thickness on the elastomeric structure.Such thickness is one which is effective in providing the desiredrelease characteristics to the coating, along with acceptable propertiesof durability, integrity and the like. Generally, the thickness of thecoating is limited only by the necessity for the elastomeric structureto maintain its flexibility. In general, it has been found that typicalcoatings range in thickness from 0.0005 to approximately 0.01 inches,though thicker coatings may be desirable in certain instances.

In some cases it is desirable to coat the entire surface of theelastomeric structure with the release coating. In other cases, it maybe more convenient, desirable and economical to coat only the portion ofthe structure which comes in contact with the article or goods to bereleased. In such cases, as little as 10 percent of the surface area maybe coated up to approximately 90-95 percent or even more of the surface.Generally, the outer surface of such structures as bags, bladders andthe like are coated; in certain instances, however, it may be desirableto coat the inner or both the inner and outer surfaces in whole or part.Usually the upper surface of belts and similar components are closed.

Prior to curing the solvent is allowed to evaporate either under ambientconditions or at convenient elevated temperatures. In either case, careis taken to ensure adequate ventilation. Such evaporation processes aretypically carried out in many situations and are well known to those ofskill in the art and present no problems in the practice of the presentinvention.

After application by suitable techniques and solvent evaporation, ifapplicable, the releasing surface coatings of the present invention areoptionally cured by any convenient technique. In certain instancesstorage for a relatively long period of time (e.g., 10 days) at ambienttemperatures (15-35°C.) may be satisfactory. It is often desirable,however, to accelerate curing by using shorter times and compensatinglyhigher temperatures. For example, temperatures ranging from about35°-225°C. (65-435°F.) may be used for periods of 10-200 minutes ormore. Often it is desirable to subject the coating to some form ofrestraint during curing to prevent unintended movement and/or thedevelopment of blisters or similar defects. Many techniques suitable forthis purpose are known in the art. For example, in the case of bladders,bags, rolls and sleeves, it is possible to cross-wrap the release coatedelastomeric structure with an inert material such as tape or sheeting,and thus subjecting the structure and surface to pressure during thecuring process. It is sometimes desirable to coat such sheeting ortaping with a conventional releasing agent to prevent undesirableadhesion during this stage.

It is possible to use releasing composition components which do notrequire chemical curing agents. Radiation-curable systems can be used.Also thermoplastic chlorosulphonated polymers may functionsatisfactorily without conventional curing. It is believed in thislatter instance, curing occurs spontaneously at a relatively slow rateduring storage even though chemical curing agents are absent.

Generally, the fracture resistant release surface coating of theinvention is cured for times sufficient to provide a release coating.Often visual inspection of the coating will indicate when this conditionis reached. The coating changes from its typically shiny, wet appearanceimmediately after application to a dull, mat appearance whensufficiently cured. Of course, tactile investigations can also revealwhen a satisfactory state of cure is reached.

EXAMPLES AND DESCRIPTION OF BEST MODE

The following examples illustrate the practice of the invention but arenot intended in any way to limit its scope, as will be appreciated bythose of skill in the art. They also include a description of the bestmode of practicing the inveniton presently known. In them all parts andpercentages are by weight and temperatures in degrees centigrade unlessexpressly indicated otherwise.

EXAMPLE I

A release coating composition is prepared by mixing 100 parts ofchlorosulphonated polyethylene with 40 parts of N-660 carbon black and100 parts of a chlorinated paraffin semi-solid tackifier. An effectiveamount (approximately 2 parts) of a conventional sulphur andnitrogen-containing curing system is included. This system includesTetrone A, magnesia, and pentaerythritol (Tetrone A=dipentamethylenethiuram tetrasulfide). Added to those components as solvent/diluent is300 parts of a mixture (50/50 by volume) of perchloroethane andmonochlorotoluene. The above materials are blended until a homogeneoussolution/dispersion is obtained. This dispersion appears to be a blackliquid having the approximate viscosity of a premium motor oil.

Immediately prior to use 100 parts by volume of the solution/dispersionis diluted with 150 parts by volume of toluene to yield, afteragitation, a releasing composition of suitable viscosity. This releasingcomposition is painted on a TUB made from fabric reinforced naturalrubber to substantially cover the outer surface thereof. After airdrying, the uncured TUB is cross-wrapped with nylon tape and cured inthe usual manner at approximately 120°-150° for 45 minutes. The bladderis then installed in a TAM.

EXAMPLE II

Example I is repeated with 100 parts of chlorosulfonated polyethylenereplacement of the green tackifying agent with 70 parts of highlychlorinated polyethylene resin. The releasing properties of thecomposition are verified by painting it on a natural rubber ply and,after drying and heating at 125°C. for 90 minutes, observing thecontrolled adhesive quality of the surface towards a second naturalrubber ply.

EXAMPLE III

A mixture of three parts by volume of Chemlok 234B is diluted andagitated with two parts by volume toluene to form a homogeneous blacksolution/dispersion of appropriate viscosity. The Chemlock 234B is ablack adhesive composition containing 25 percent organic compounds,polymers and fillers dissolved or dispersed in 75 percent organicsolvent which is 50 weight percent xylene and 25 weight percenttrichloroethylene. This preparation is commercially available fromHughson Chemicals, Lord Corporation, Erie, Pennsylvania, USA. Typicalproperties of 234B are shown in Table II.

                  TABLE II                                                        ______________________________________                                        TYPICAL PROPERTIES OF CHEMLOK 234B                                            ______________________________________                                        Composition      A black adhesive composition                                                  containing organic compounds,                                                 polymers and fillers                                                          dissolved or dispersed in                                                     organic solvents.                                            Solids Content   22.5-26.5%                                                   Diluents         Xylene or toluene                                            Weight           8.9-9.2 lbs./gal. (1066-1102                                                  kg/m.sup.3)                                                  Specific Gravity 1.09                                                         Flash Point (Pensky-Martens                                                                    83° F. (28° C.)                                Closed Cup)                                                                   Viscosity: Brookfield Model                                                                    450-800 cps                                                  LVT, No. 2 spindle at 30                                                                       (.450-.800 Pa.s)                                             rpm at 25° C. (77° F.)                                          Shelf Life       At least one year.                                           ______________________________________                                    

Chemlock 234B is further analyzed by independent means. The residue uponsolvent evaporation (about 25 percent) exhibits an infrared spectrumwith major absorption peaks as shown in Table III.

                  TABLE III                                                       ______________________________________                                        Major Absorbtions in Infrared Spectrum of Chemlok 234-B                       Residue (evaporated a KBr Plate), CM.sup.-1                                   ______________________________________                                        2940            1260   780                                                    2860            1100   575                                                    1485            1100   485                                                    1420            865                                                           ______________________________________                                    

Further analysis of Chemlok 234B is accomplished by diluting a samplewith toluene and centrifuging. The nondissolved material (5.6%),apparently carbon black and other materials, has an elementalcomposition of percent carbon, 62.93; percent hydrogen, 2.32; percentnitrogen, 17.07. The supernatant, toluene soluble portion appears to bea pale yellow solution. Addition of a large of volume of methanolproduces at coagulated polymer. This methanol insoluble polymer has anelemental composition of: percent carbon, 47.06%, percent hydrogen,8.40; percent nitrogen, 0.06; percent chlorine, 40.2; percent sulphur,0.95-1.09. Infrared and NMR analysis indicates this methanol insolublepolymer is chlorosulphonated polyethylene. The spectrum corresponds tothe spectrum of chlorosulphonated polyethylene found in standardpublished spectra atlases. Thermogravimetric analysis and the T_(g) ofthe polymer (-23°C.) are consistant with this identification.

The supernatant from the methanol coagulation is evaporated to provide amethanol and toluene soluble resinous material. Infrared and NMRanalysis indicates this material is a chlorinated polyethylene of lowmolecular weight and/or a chlorinated terpene type resin. The resin issemi-solid, tacky and pleasantly odiferous. Comparison of its IR and NMRspectra with those published are consistent with this identification.Further analysis of Chemlok 234B as commercially available shows it tocontain 24.65 percent solids after evaporation of the solvents. Thissolid fraction exhibits the following elemental analysis; percentcarbon, 45.49; percent hydrogen, 4.28; percent nitrogen, 3.36; percentsulphur, 0.5; percent chlorine, 42.3; percent ash (normal), 0.59;percent methanol soluable, 43.80; percent toluene soluable, 37.45Thermogravimetric analysis indicates percent carbon black, 22.6; andpercent ash, 0.70. The ash is also shown to contain magnesium.

The aforedescribed mixture of Chemlock 234B and toluene is used as areleasing composition of the present invention. It is painted on theouter surface of the TUB and the TUB then cured with cross-wrapping in aconventional manner. The TUB is then used in a factory TAM to produce anaverage of 6,000 tires. During this production run, the bladders withthe releasing coating of this invention are observed to give good, tightturn-ups and to perform without cracking or other problems.

EXAMPLE IV

This example is carried out in essentially the same manner as ExampleIII except Chemlok 234B-E is used in place of Chemlok 234B. Chemlok234B-E is also available from the same source as 234B and is understoodto contain the same active ingredients as 234B. The solvent system,however, is modified to be exempt from certain health and environmentalregulations and constitutes monochlorotoluene and perchloroethylenerather than xylene or toluene and trichloroethylene. Typical propertiesat Chemlok 234B-E are shown in Table IV. The release coating formedexhibits satisfactory performance when it is evaluated in a laboratoryscreening test.

                  TABLE IV                                                        ______________________________________                                        Typical Properties of Chemlok 234B-E                                          ______________________________________                                        Viscosity, Brookfield Model LVT                                                                     550-650 cps                                             No. 2 spindle at 30 RPM, 77° F. (25° C.)                                              .550-.650 s/M.sup.2                                     Solids Content        20-22%                                                  Color                 Black (liquid)                                          Weight                10.4-11.0 lbs./gal.                                                           1258-1306 Kg/M.sup.3                                    Diluents              Perchloroethylene                                                             and                                                                           Monochlorotoluene                                       Flash Point (Pensky-Martens Closed Cup)                                                             103° F. (39° C.)                          ______________________________________                                    

EXAMPLE V

A turn-over bladder is constructed in substantially the manner describedby Johnson in U.S. Pat. No. 4,381,331 (which is hereby incorporated byreference herein) to an intermediate stage of manufacture before finalcuring. After calendaring the textile fabric covering with a coat ofuncured and unvulcanized rubber (see column 1, lines 45-62 of Johnson),the uncured rubber coated surface is painted with the release coatingcomposition of Example III. The bladder is vulcanized in the mannerdescribed by Johnson; it is not, however, abraded or otherwise treatedto remove rubber in any manner. The cords of the bladder do not projectabove the surface of the rubber substrate, and in fact lie beneath thecured release coating.

The bladder is used successfully in a TAM to make more than 3,000 tires.

The elastomeric structures of this invention can be made of naturalrubber, synthetic rubber or mixtures thereof with each other and/orother materials which do not substantially impair their elastomerenature.

What is claimed is:
 1. A bladder, for use in a tire assembly machinehaving about 10-90% of its outer surface bearing an exposed releasingsurface coating of release-effective thickness formed by the methodcomprising the steps of:(I) Applying to the outer surface of the bladdera releasing composition comprising:(a) a chlorosulphonated polyethylenehaving a Mooney viscosity of about 30-160; (b) a carbon black or silicareinforcing filler; (c) a green tackifying agent; and optionally (d) asuitable chemical curing system; and optionally (e) a first inert,volatile solvent/diluent viscosity-reducing vehicle for components(a)-(d), and optionally (f) a second, inert volatile solvent/diluentviscosity-reducing vehicle; (II) Removing a sufficient amount ofvehicles present to leave a coherent, adhering film on the surface; and(III) Curing the film to form the exposed releasing coating consistingessentially of said chlorosulphonted polyethylene (a), said carbon blackor silica filler (b), said green tackifying agent (c) and optionallysaid chemical curing system (d).
 2. A turnup bladder as claimed inclaim
 1. 3. A fabric reinforced turnup bladder, TUB, for use in a tireassembly machine, having at least about 10-95% of its surface coveredwith a fracture-resistant, exposed releasing surface of releaseeffective thickness for an elastomeric structure formed by the methodwhich comprises the steps of:(I) Applying Chemlok 234B or 234B-E in aninert solvent/diluent vehicle to at least a portion of the surface ofthe bladder; (II) Removing by evaporation at about 20°-75° Centigrade asufficient amount of the vehicle present to leave a coherent, adheringfilm on the surface; and (III) Curing the film to form the exposedreleasing coating consisting essentially of said Chemlok 234B or 234B-E;wherein said Chemlok 234B is a black adhesive composition containingapproximately 25 weight percent of a carbon-, hydrogen-, nitrogen-,sulfur-, and chlorine-containing reside dissolved or dispersed in 50weight percent xylene and 25 weight percent trichlorethylene, saidresidue exhibiting: (a) major absorptions in its Infrared spectrum(evaporated on a KBr plate) at 2940, 2860, 1485, 1420, 1260, 1100, 1010,865, 780, 575 and 485 cm⁻¹ ; (b) the following elemental analysis inweight percent: carbon, 45.49; hydrogen, 4.28; nitrogen 3.36; sulfur0.5; and percent chlorine, 42.3; and (c) the following properties inweight percent: ash (normal) 0.59; methanol soluble, 43.80; toluenesoluble, 37.45; said ash also containing magnesium and; wherein Chemlock234B-E is the same as Chemlok 234B except it contains approximately20-22 weight percent of said residue and monochlorotoluenetrichloroethylene.